Drug-alcohol interactions on psychomotor skills: zopiclone and flunitrazepam.

Interaction between alcohol and zopiclone or flunitrazepam as well as the residual effects of both these hypnotics were studied in 20 normal male volunteers who received each 3 of 6 different drug and drink combinations according to a balanced incomplete block design as follows: placebo, zopiclone (7.5 mg), or flunitrazepam (2 mg) was administered double-blind in identical capsules at 23.00 h, and 0.5 g/kg body weight of alcohol or placebo alcohol was given at 08.30 h the following morning. Psychomotor skills of the volunteers were measured before drinking and 30 min, 1.5 h and 2.5 h after it. As compared with placebo, zopiclone had no residual effects, while flunitrazepam had some effects on standing steadiness, tracking, and flicker recognition. Alcohol alone had a non-significant effect on skills, and the combination zopiclone plus alcohol behaved as alcohol alone. Flunitrazepam plus alcohol impaired significantly standing steadiness, tracking, and reactive skills when compared with all other treatments. Time anticipation and hand and foot proprioception were not affected by any treatment. The results suggest that flunitrazepam, unlike zopiclone, has residual effects and interacts with alcohol in the morning following overnight ingestion of the drug.